Mary greeted and welcomed everyone, and told them to be silent. One person spoke, followed by a second, and then another. Mary then shouted at the first person to have spoken after her, but did not shout at anyone else. Why did she not shout at anyone else?

Does angry Gary put on heels and become angry Mary? LOL No. Mary is his third cousin twice removed. But that's irrelevant ;-)

are any of the anonymous speakers Mary? Nodid anyone ask a question? Nodid anyone answer a question? Noafter #2 spoke Did Mary tell #2 to be quiet? Mary never told a second speaker to be quiet.were #1 and #3 expected to speak? No-one was expected to speak.

just to clarify... would this sequence work.. Mary greeted and welcomed everyone, and told them to be silent.. #1 spoke, then #2 spoke, then Mary yelled, then #3 spoke? No

how about this.. Mary greeted and welcomed everyone, and told them to be silent.. #1 spoke, then #2 spoke, then #3 spoke then Mary yelled at #3 ? No

are there any relevant items in the classroom? No

Different languages again? No :-p

Did person #1 deliberately mistranslate Mary's instruction? NoEg: Mary says: "Silence in class" to a bunch of French children, and #1 says 'Elle a dit "parlez entre vous"'? No

would Mary have yelled if #2 & #3 were silent? Only one person needed to speak for Mary to yell.

were 2 and 3 trying to silence 1? No-one tried to silence 1

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Just to clarify earlier answer in case anyone was being confused by it: were #1 and #3 expected to speak? - I said no-one was expected to speak - technically, Mary was expected to speak, so I should really have said no-one except Mary was expected to speak. Anyway, that's not really important, so play on :-)

-----Spoiler-----Answers to sixtyeight's questions below, which fairly much complete the puzzle when put together. Well discovered, sixtyeight, thought I might be able to string you all along for a little longer ;-)